In fuel receptacles of vehicles, such as aircraft, fasteners penetrating the fuel receptacle must be electrically insulated to protect the vehicle from electromagnetic effect (EME) phenomena, e.g. lightning strikes. Conventionally, portions of fasteners protruding inside the fuel receptacle are provided with sealing (seal) caps for purposes of mitigating EME phenomena and/or for addressing other sealing requirements, if any.
Some seal caps are formed by manually discharging (daubing) a volume of viscous curable sealant over each fastener. However, seal caps formed using the daubing process may not meet critical dimensional requirements due to slumping of uncured sealant.
Alternatively, seal caps may utilize a pre-cured exterior shell, the installation of which requires several time-consuming steps, such as cleaning, pre-filling with viscous sealant, locating over a fastener, and careful application to the fastener to achieve squeeze-out of sealant from the shell in an effort to eliminate voids and entrapped air within the sealant. Specification requirements necessitate removal and/or smoothing (fairing) of squeezed-out sealant, further increasing manufacturing cycle time. Regardless of the fabrication method, conventional seal caps invariably require inspection, with time-consuming rework often being necessary.